Conventional archaeological excavation methods are, by design, extremely invasive and result in culturally sensitive areas being irrevocably altered. For this reason, near-surface geophysical techniques have been incorporated into archaeological investigations to aid in locating buried features and developing specific excavation plans with minimal damage to the sites. The objective of our research was to conduct a geophysical surveying campaign at a test site in Knoxville, Tennessee, to develop a workflow for an improved data management methodology that would be applied to data acquired at an active archaeological site in Cyprus. A multi-tool geophysical survey was completed as a first case study at a control site with known subsurface features on the University of Tennessee Agricultural Campus using both ground penetrating radar and magnetic gradiometry. Using real-time differential corrected GPS data, we systematically imported the images into Google Earth as accurately georeferenced overlays on existing topographic maps and air photos. We added placemarks where we interpreted subsurface anomalies based on the data, exported waypoints for the features into spreadsheet software, and correlated the results to the known locations. We next tested this methodology with data from an active archaeological site in southern Cyprus. Data were displayed in Google Earth and accurate GPS coordinates for features were exported into a spreadsheet file. We were able to share a tested, easily accessible final product that was immediately useful and accessible to the archaeologists on the team and the broader archaeological community.

Abstract Applications of seismic time-lapse techniques generally are constrained to large-scale investigations associated with petroleum exploration and exploitation. There is growing interest in using geophysical methods to monitor nearsurface phenomena, such as fluid flow in fractured or karstic bedrock, hydraulic infiltration, and anthropogenic manipulations during environmental remediation. Previous near-surface geophysical time-lapse studies have focused on electrical or electromagnetic (EM) techniques (including ground-penetrating radar) or borehole methods. To evaluate the utility of surface seismic time-lapse traveltime tomography, a site was monitored through time along a single 2D profile. The objective was to attribute increases in seismic P-wave velocity with the development of perched water bodies in the upper 4 m of the subsurface. The study was conducted in the Y-12 area of Oak Ridge National Laboratory in Tennessee, U.S.A., in conjunction with a broader multidisciplinary investigation on the fate and transport of contaminants. Because of previous anthropogenic alterations of the site associated with remediation efforts (e.g., replacing as much as 7 m of contaminated soil with poorly sorted limestone gravel fill during construction of a seepage basin cap), the near-surface hydrogeology was extremely heterogeneous and was hypothesized to have a large influence on differential infiltration, contaminant distribution, and contaminant remobilization. The seismic data were processed using a wavepath eikonal traveltime (WET) tomography approach, and a modified trend-analysis technique was applied to remove the larger spatial component associated with geologic variability. The final “residual” velocity-anomaly images were compared with wellbore hydrologic data and error analyses and were used to interpret the presence and geometry of perched water in the shallow subsurface. The study suggests that velocity estimates obtained from surface-seismic traveltime tomography methods are effective for indicating the spatial and temporal distribution of perched water bodies at the Oak Ridge site in the upper 4 m of the subsurface.

Ground penetrating radar (also referred to as GPR, ground probing radar, or georadar) is a near-surface geophysical tool with a wide range of applications. Over the past 30 years, GPR has been used successfully to aid in constraining problems in diverse fields such as archaeology, environmental site characterization, glaciology, hydrology, land mine/unexploded ordinance detection, sedimentology, and structural geology. In many cases, however, GPR surveys have been planned or executed with little or no understanding of the physical basis by which GPR operates and is constrained. As a result, many unsuccessful GPR studies have also been presented or published over the past 30 years. The objectives of this primer are to (1) provide an introduction to the important variables pertinent to GPR and (2) to explain the relevant aspects of these variables in GPR acquisition, in an attempt to provide fundamental knowledge for improving GPR usage in the future.

Linear dunes are the most abundant type of desert dune and the dominant land-form on the continent of Australia. This paper reports the results of GPR surveys across linear dunes in the deserts of central Australia including parts of the Simpson and Strzelecki deserts. The GPR data suffered from severely limited penetration and poor resolution due to signal attenuation associated with a high proportion of mud, which, probably due to progressive illuviation, increases with dune age. However, although such conditions prevail in much of central Australia, useful stratigraphic information can still be obtained there using GPR. Buried palaeosol horizons within dunes have been identified, and taken in conjunction with thermoluminescence (TL) ages from the dunes, it is possible to make some interpretations of linear dune evolution. TL ages show that some dunes are older in the south and young toward the north. It is possible to place some constraints on rates of vertical, lateral, and dune-front accretion within the linear dunes with ∼2–6 m, 0–50 m and 3000 m, respectively, over the last ca. 10 ka. The combination of GPR profiles and TL dating of linear dunes in the Simpson and Strzelecki deserts confirms Holocene modification of preexisting linear dunes with minor easterly accretion that has contributed to the asymmetry of vegetated linear dunes in central Australia. The results support the hypothesis that linear dunes in Australia are composite forms with a long and sometimes complex history.

Ground penetrating radar (GPR) was used to investigate the internal structure and development of an active parabolic sand dune in the Bigstick Sand Hills of southwestern Saskatchewan, Canada. The radar survey was conducted in a grid configuration using 250 MHz antennas. The radar frequency and the properties of the aeolian sands limited the penetration of the radar signal to the uppermost 4 m. Radar profiles parallel to the prevailing westerly wind reveal three zones with differing structural arrangements that are interpreted to represent three phases in the development of the dune: (1) underlying low-angle reflections representing preexisting aeolian strata associated with sand sheet or dune marginal deposition; (2) high-angle reflections representing downwind migration by grainflow; and (3) a variety of high- and moderate-to-low-angle reflections representing a more complex pattern of migration involving grainflow, grainfall, and ripple deposition. Radar profiles perpendicular to the prevailing wind are characterized by convex-up and concaveup reflections along the dune head and are interpreted as spur and trough structures, respectively. Radar profiles over the wings reveal an arrangement of high-angle reflections radiating away from the center of the dune. The main structural features from the radar profiles are summarized into two radar surfaces; three radar packages; and three radar facies, one of which has two subfacies. Observations of exposed surface stratigraphy following extensive wind erosion lend support to the interpretations made from the GPR data.

A systematic pattern of beach ridges forming strandplains commonly fills embayments in the Great Lakes of North America. Ground penetrating radar (GPR) and vibracore results define a common preserved architecture inside beach ridges. Comparing the preserved architecture with a conceptual model of beach-ridge development explains the conditions responsible for their development and preservation. Great Lakes beach ridges are a product of a positive rate of sediment supply and a multidecadal fluctuation in lake level. Many shoreline behaviors occur throughout the development of a beach ridge, but not all successions originally formed by these behaviors are preserved. Beach ridges are stratigraphically separated by concave lakeward-dipping ravinement surfaces extending at depth below beach-ridge crests to the ground surface in adjacent landward swales. These surfaces are formed during rapid rises in water level, where previously laid deposits erode, forming a base for the beach-ridge core. As the rate of rise decreases and the water-level elevation approaches a highstand, the core of the ridge is built by vertical aggradation. Subsequent deposits build lakeward during progradation when water levels become stable, protecting the core from being eroded during future rapid rises in water level. Dune sand deposits on beach-ridge cores are stabilized by vegetation, and swales are commonly filled with organic material.

Ground penetrating radar (GPR) records of groundwater surface (GWS) reflections have been analyzed from 40 across-barrier profiles, totaling 50 km in combined length, taken from barrier spits and beach plains of the Columbia River littoral system. The barriers and beach plains host shallow fresh-water aquifers in the prograded beach deposits and abandoned foredune ridges, totaling 10–30 m in thickness. Study results demonstrate that GWS reflections could be traced continuously at subsurface depths of 1–15 m with the GPR 100 MHz and 50 MHz antennae using 400 V and 1000 V transmitters. Boreholes (62 in number) and lake water levels (24 in number) provide ground-truthing of the across-barrier GWS trends interpreted from the GPR profiles. The GWS rises in elevation (4–8 m above base level) under high, broad foredune-ridges and drops under interdune ridge valleys (1–3 m above base level). Continuous profiles of GWS demonstrate that lakes, ponds, and bogs of the barriers and beach plains are “windows” into the shallow coastal aquifer. The GPR records demonstrate that the GWS slopes either to seaward (0.003–0.04 gradient) or to landward (0.001–0.05 gradient) from divides under the largest, shore-parallel dune ridges in the barriers. The GWS gradients indicate that subsurface contaminant transport from the developed dune ridges will be intercepted by intervening lakes and ponds in the interdune-ridge valleys. The GPR records also establish the effect of drainage ditches in lowering GWS elevations (1–2 m) in sensitive wetlands located 100s of meters in distance from the constructed ditches.

In eastern coastal Maine, many flat-topped landforms, often identified as glacial-marine deltas, are cultivated for blueberry production. These agriculturally valuable features are not exploited for aggregate resources, severely limiting stratigraphic exposure. Coring is often forbidden; where permissible, coarse-grained surficial sediments make coring and sediment retrieval difficult. Ground penetrating radar (GPR) has become an invaluable tool in an ongoing study of the otherwise inaccessible subsurface morphology in this region and provides a means of detailing the large-scale sedimentary structures comprising these features. GPR studies allow us to reassess previous depositional interpretations and to develop alternative developmental models. The work presented here focuses on Pineo Ridge, a large, flat-topped ice-marginal glacial-marine delta complex with a strong linear trend and two distinct landform zones, informally termed East Pineo and West Pineo. Previous workers have described each zone separately due to local morphological variation. Our GPR work further substantiates this geomorphic differentiation. East Pineo developed as a series of deltaic lobes prograding southward from an ice-contact margin during the local marine highstand. GPR data do not suggest postdepositional modification by ice-margin re-advance. We suggest that West Pineo has a more complex, two-stage depositional history. The southern section of the feature consists of southward-prograding deltaic lobes deposited during retreat of the Laurentide ice margin, with later erosional modification during marine regression. The northern section of West Pineo formed as a series of northward-prograding deltaic lobes as sediment-laden meltwater may have been diverted by the existing deposits of the southern section of West Pineo.

Relict deltas of well-sorted and well-drained sands are among numerous strand-line deposits that mark the former shoreline positions of glacial Lake Iroquois in northern New York. In this study, ground penetrating radar (GPR) was used to image the subsurface architecture of four Late Pleistocene lacustrine deltas to provide information about their depositional environment. The surveyed deltas indicate two distinct glacial Lake Iroquois water levels, the Frontenac and Trenton water phases. A pulseEKKO 100 GPR unit and a 400 Vtransmitter, combined with 50 and 100 MHz antennas are used to provide a better understanding of the internal structures, delta thickness, and distinct facies units. Delta thickness varies generally from 10 to >20 m. High-resolution GPR profiles exhibit variable reflection continuity. Depositional patterns of four distinct radarfacies are described as being characteristic of foreset bed, braided channel, channel cut and fill, and lacustrine clay, in addition to fine-grained till deposits. Facies units reflect an environment of a braided delta in which high sediment volumes and unstable directions of deposition dominated. Larger boulders of nonriverine origin that are located within deltaic sediments are interpreted as dropstones. Waterlevels of glacial Lake Iroquois appear to be stable during the relatively short periods of delta formation. Deltas of glacial Lake Iroquois exhibit lobate morphology typical of a constructive environment.

Field, map, and aerial photoreconnaissance in the Lake Alvord basin has focused on identifying late Pleistocene depositional shoreline features (e.g., tombolos, spits, barriers). Features in different areas of the basin are well defined, and their spatial extents are easily mapped; however, absolute—or even relative—ages of shoreline features are not clear. Ground penetrating radar (GPR) was used to distinguish between intermediate and highstand stage shorelines during what is thought to have been the latest Pleistocene, threshold-controlled lake cycle. Radar transects of 280 and 600 m imaged a spit and a baymouth barrier at sites in the northeastern quadrant of the basin where transects were aligned normal to the strike of each depositional geomorphic feature. Signal penetration with 100 MHz antennas was shallow (∼4 m), but resolution was sufficient to locate and identify gross morphostratigraphic features. Flooding surfaces are shown to correspond to intermediate stage lake surface elevations, and the absence of a flooding surface at the elevation of the highest shoreline indicates this to be the maximum lake surface elevation during this cycle. Elevations of intermediate lake stage elevations and highstand stage elevations were consistent at the two sites, with the highstand elevations corresponding closely to the basin threshold at Big Sand Gap. These data provide a first-order approximation of lake stage sequence and the degree of postdepositional neotectonic activity and illustrate the utility of GPR when used in context with field measurements in distinguishing transgressive and highstand features.

The internal architecture of sandbars in modern braided streams has not been adequately documented, especially in medium-scale braided rivers. Identification of the architecture and development of an understanding of the formative processes for these macroforms is important for (1) understanding sedimentation in braided streams, (2) understanding reservoir and aquifer compartmentalization in ancient deposits, and (3) predicting the controls on deposition in similar settings. A 225 MHz GPR survey was conducted within a braided reach of the Wisconsin River near Spring Green, Wisconsin, USA, to characterize the subsurface architecture of a midchannel bar. A 20 × 20 m survey grid consisting of sixteen GPR transects oriented approximately in flow-parallel and flow-transverse directions was established on the bar. Three-dimensional analysis of the GPR profiles resulted in the interpretation of five major radar facies that represent depositional mechanisms that controlled bar growth and modification. Vertical accretion (aggradation) was the primary depositional mechanism for bar growth and was augmented by much smaller amounts of downstream accretion, lateral accretion, and upstream accretion. A channel fill pattern was also recognized and correlated between multiple profiles, and it provided evidence for two preexisting, independent macroforms that converged to form the studied bar. The work provides insight into bar morphology within sandy braided reaches that closely resembles that of similar GPR studies performed in both smaller and larger rivers and supports a scale-independent model for some aspects of bar growth and modification in sandy, braided rivers.

A ground penetrating radar (GPR) survey was used to image the fluvial architecture within a buried paleovalley at Maple Creek, Guyana. The survey was part of a larger study of the stratigraphy and organization of fluvial elements within the valley fill. The survey consisted of 44 km of 50 and 100 MHz GPR profiles collected in a grid pattern. The 100 MHz antennae were used where depth to bedrock was less than 20 m, and the 50 MHz antennae were used where depth to bedrock exceeded 20 m. The survey grid consisted of 28 east-west–trending transects and 6 north-south–trending transects. East-west transects in the southern part of the study area were spaced 100 m apart. Those in the northern part of the study area were spaced 400 m apart, and north-south cross-transects were spaced at 500 m intervals. The survey imaged two strong reflectors interpreted to represent major bounding surfaces. The lower surface was confirmed to be the bedrock-sediment interface defining the valley boundary. The second major surface is the boundary between the fluvial valley fill and overlying bleached sand correlative with the White Sand Formation. In addition to the major surfaces, several minor surfaces were also imaged, resulting in the identification of 21 radar elements. Sixteen of the elements were interpreted to represent fluvial architectural elements. Four distinct morphological zones were recognized and were differentiated by variation in the geometry of the bedrock-sediment interface and by distinctive assemblages of architectural elements.

A thick sequence (∼177 m) of aggradational deposits was studied in the lower Hope Valley. Valley fill is preserved in a tectonic depression, which is associated with a releasing bend on the active strike slip Hope Fault. Our results indicate that local basin subsidence since the last glacial maximum (LGM) occurred at a rate of 1.4–2.5 mm/yr, which roughly matches the regional tectonic uplift rate. The approximate balance between uplift and basin subsidence resulted in a local late Pleistocene sedimentary pattern that was primarily controlled by climate-induced processes of aggradation and degradation. Here we describe deposits and subsurface sedimentary structures from an exposure located near Glynn Wye on the southern side of the Hope Valley. Sediments at the base of the studied sequence comprise 55 m of lacustrine/deltaic deposits that are overlain by thick fluvial and glaciofluvial gravels. Infrared stimulated luminescence (IRSL) dating on the lake beds yielded an age of 60.3 ∼5.6 ka BP, suggesting late OIS 4 ( oxygen isotope stage ) age for the lake. A subsequent phase of fluvial aggradation buried paleolake deposits under 65 m of glaciofluvial outwash. This was followed by the progression of a glacial advance which deposited a moraine over the top of the sequence. A luminescence age (IRSL) of 32.1 ∼2.6 ka BP from the outwash deposit below the moraine indicates that glaciofluvial aggradation prior to the ice incursion was well advanced during late OIS 3. Postglacial fluvial degradation caused 160 m of incision into the lower Hope Valley, thereby partially excavating the deeper basin fill.

We used ground penetrating radar (GPR) data to help determine the spatial distribution and the subsurface geometry of clastic dikes at the Hanford Site. This information will help to improve the understanding of the hydrological role of these ubiquitous clastic dikes at the Hanford Site. We collected 100 MHz ground penetrating radar (GPR) 3-D surface reflection data at two sites, the 216-S-16 (S-16) Pond and the Army Loop Road sites, and 2-D reflection data along a 6.9 km linear transect (Traverse site) near the Army Loop Road site. The dikes are distinguished in the GPR data by a strongly attenuated zone, disruptions in the continuity of reflections, and diffractions where reflections are disrupted. In general, the data quality is better at the Army Loop Road and Traverse sites than at the S-16 Pond site, probably due to the presence of cobbles at the S-16 Pond site. A high-moisture, fine-grained unit probably causes the strong reflections at the Army Loop Road site and the Traverse survey site. The signal penetration varies between 5 and 12 m below the land surface.

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Abstract This document can either be printed or followed as an Adobe Acrobat PDF file (included on the CD-ROM). As a PDF file, each item on the Contents page is linked to its corresponding location, and the user can return to Contents by clicking the Page Number at the bottomcenter of every page. Additionally, all references in this tutorial are linked to the appropriate location in Appendix A (the Reference list). The main portion of this tutorial is Section 2, Processing Steps and Associated Pitfalls, which focuses on individual processing procedures, each of which is broken into three parts: The Process The basics of the process are discussed briefly with graphical examples when appropriate. Applying the Process The procedure is applied to the Kansas or England example data with emphasis on the most important parameters. Pitfalls Associated with the Process Potential processing pitfalls associated with the procedure are explained, using examples where applicable. The seismic data examples in this Primer were processed and displayed using Seismic Processing Workshop (Parallel Geoscience Corporation) on a Macintosh G3 computer. 1.2 Near-Surface Seismic-Reflection Data Processing The first published examples of seismic reflections detected shallower than 50 m are from Pakiser and others at the U.S. Geological Survey (Pakiser and Mabey, 1954; Pakiser et al., 1954; Pakiser and Warrick, 1956; Warrick and Winslow, 1960). Digital seismographs were not yet available, and the method was not strongly pursued until the late 1970s and early 1980s. A classic paper by Hunter et al. (1984) developed the optimum-window technique, first used for